SUSY dark matter annihilation in the Galactic halo

TL;DR

This paper investigates how dark matter clumps formed from initial density perturbations can survive in the Galactic halo, potentially boosting signals from neutralino annihilation detectable as gamma-rays, positrons, and antiprotons.

Contribution

It models the formation, survival, and distribution of small-scale dark matter clumps in the Galactic halo, highlighting their role in enhancing indirect detection signals.

Findings

A small fraction (~0.1%) of dark matter clumps survive hierarchical clustering.

Surviving clumps can significantly boost annihilation signals.

Tidal destruction influences the anisotropy of clump distribution.

Abstract

Neutralino annihilation in the Galactic halo is the most definite observational signature proposed for indirect registration of the SUSY Dark Matter (DM) candidate particles. The corresponding annihilation signal (in the form of gamma-rays, positrons and antiprotons) may be boosted for one or three orders of magnitude due to the clustering of cold DM particles into the small-scale and very dense self-gravitating clumps. We discuss the formation of these clumps from the initial density perturbations and their successive fate in the Galactic halo. Only a small fraction of these clumps, $\sim0.1$%, in each logarithmic mass interval $\Delta\log M\sim1$ survives the stage of hierarchical clustering. We calculate the probability of surviving the remnants of dark matter clumps in the Galaxy by modelling the tidal destruction of the small-scale clumps by the Galactic disk and stars. It is demonstrated that a substantial fraction of clump remnants may survive through the tidal destruction during the lifetime of the Galaxy. The resulting mass spectrum of survived clumps is extended down to the mass of the core of the cosmologically produced clumps with a minimal mass. The survived dense remnants of tidally destructed clumps provide an amplification (boosting) of the annihilation signal with respect to the diffuse DM in the Galactic halo. We describe the anisotropy of clump distribution caused by the tidal destruction of clumps in the Galactic disk.